An organic EL display panel includes a plurality of organic EL devices formed on a substrate, each of which typically includes a pair of electrodes consisting of pixel electrode (anode) and a cathode, and functional layers such as an organic emitting layer between the electrodes. The electrodes and functional layers are generally formed by vapor deposition, sputtering or other method, but can also be formed by coating method.
Formation of the electrodes and functional layers by coating method involves application and drying of liquid substances in regions defined by bank made of insulating material. Failure to appropriately control the bank's surface affinity for the liquid substances often leads to low uniformity in the resultant layer's thickness. This in turn leads to poor image characteristics in the manufactured organic EL display panel due in part to brightness unevenness.
In general, the bank top surface needs to be lyophobic in order for the applied liquid substance to be retained in the region defined by the bank. However, when the bank inner side surface is lyophobic, the applied liquid substance fails to spread to the desired region, which results in low uniformity in the resultant layer's thickness. Accordingly, a lower side of the bank inner side surface of the bank is preferably lyophilic, while a upper side of the inner side surface of the bank is lyophobic.
To achieve this, two-layered banks have been reported in which the lower layer is made lyophilic and the upper one is made lyophobic (see Patent Documents 1 to 5). For example, these literatures describe supplying liquid substances in regions defined by two-layered bank consisting of a lower layer made of inorganic material and a upper layer made of organic material or the like, to form therein functional layers such as an organic emitting layer. Moreover, techniques have also been known that form a lyophobic organic film only on the upper layer of the two-layered bank (see Patent Documents 6 and 7).
Further, methods of selective modification of surface properties by light radiation of a thin organic film formed on the surface are known (see, e.g., Patent Document 8). Such a thin organic film is sometimes referred to as a “self-assembled thin organic film.” For example, self-assembled thin organic films are known that undergo molecular structure changes on exposure to UV light to alter the water contact angle at the exposed surface.
Techniques have been known that form self-assembled thin organic films on bank surrounding coating region in which functional layer is to be formed by a coating method (see Patent Documents 9 and 10). Patent Document 9 reports a method of photo-patterning of a lyophobic, self-assembled thin organic film provided over entire surface of partitioning wall (bank) in such a way that the self-assembled thin organic film exclusively remains on the bank top surfaces.    Patent Document 1: Japanese Patent Application Laid-Open No. 2004-171007    Patent Document 2: Japanese Patent Application Laid-Open No. 2005-326799    Patent Document 3: U.S. Patent Application Publication No. 2005/0116632    Patent Document 4: Japanese Patent Application Laid-Open No. 2006-216297    Patent Document 5: U.S. Patent Application Publication No. 2006/017038    Patent Document 6: Japanese Patent Application Laid-Open No. 2007-95512    Patent Document 7: U.S. Patent Application Publication No. 2007/0071885    Patent Document 8: Japanese Patent Application Laid-Open No. 2006-188487    Patent Document 9: Japanese Patent Application Laid-Open No. 2002-237383    Patent Document 10: U.S. Patent Application Publication No. 2002/0016031